Revista Chilena de Neurocirugía 42: 2016 Callosotomía: técnicas, resultados y complicaciones. Revisión de la literatura Callosotomy: techniques, results and complications - Literature Review Paulo Henrique Pires de Aguiar1,3,4,5, Alain Bouthillier2, Iracema Araújo Estevão6, Bruno Camporeze6, Mariany Carolina de Melo Silva6, Ivan Fernandes Filho7, Luciana Rodrigues8, Renata Simm8, José Faucetti9. 1 Division of Neurosurgery, Santa Paula Hospital - São Paulo - SP, Brazil. 2 Division of Neurosurgery, Department of Surgery, University of Montreal - Quebec, Canada. 3 Division of Neurosurgery, Oswaldo Cruz Hospital - São Paulo - SP, Brazil. 4 Division of Post-Graduation, Department of Surgery, Federal University of Rio Grande do Sul - Porto Alegre - RS, Brazil. 5 Professor of Neurology, Department of Neurology, Pontifical Catholic University of São Paulo - Sorocaba - SP, Brazil. 6 Medical School of São Francisco University - Bragança Paulista - SP - Brazil. 7 Medical School of Pontifical Catholic University of São Paulo - Sorocaba - SP, Brazil. 8 Division of Neurology of Santa Paula Hospital - São Paulo - SP, Brazil. 9 Medical artist at the University of São Paulo - São Paulo - SP, Brazil. Rev. Chil. Neurocirugía 42: 94-101, 2016 Abstract Background: Patients with intractable seizures who are not candidates for focal resective surgery are indicated for a pallia- tive surgical procedure, the callosotomy. This procedure is based on the hypothesis that the corpus callosum is an important pathway for interhemispheric spread of epileptic activity and, for drug resistant epilepsy. It presents relatively low permanent morbidity and an efficacy in the control of seizures. Based on literature, the corpus callosotomy improves the quality of life of patients that has the indication to perform this procedure because it allows reducing the frequency of seizures, whether tonic or atonic, tonic-clonic, absence or frontal lobe complex partial seizures. Aim: The aim of this literature review is discuss the technical details, modalities, risks, complications, results as well de prognosis of callosotomy based on critical literature review and the authors experience. Casuistry and Methods: It was performed bibliographical consultation, using the data- bases MEDLINE, LILACS, SciELO, utilizing language as selection criteria, choosing preferably recent articles in Portuguese, Spanish or English, with publication year higher than 2000. Conclusion: According to author’s experience and references, callosotomy is a safe procedure when indicated to selected cases and the success rate is proportional to the extent of cal- losal resection. A greater resection can reduce the seizure frequency, however the morbidity may also be larger. There is no important study comparing VNS versus Callosotomy versus VNS plus callososotomy, what would be for future necessary for an important source of data about this topic. Key words: Drug Resistant Epilepsy, Drug Refractory Epilepsy, Corpus Callosum. Resumen Introducción: Los pacientes con convulsiones intratables que no son candidatos para la cirugía de resección focal están indicados para un procedimiento quirúrgico paliativo, la callosotomía. Este procedimiento se basa en la hipótesis de que el cuerpo calloso es una importante vía para la propagación interhemisférica de la actividad epiléptica y, para la epilepsia resis- tente a fármacos. Presenta relativamente baja morbilidad permanente y una eficacia en el control de las convulsiones. Sobre la base de la literatura, la callostomía mejora la calidad de vida de los pacientes que tiene la indicación para realizar este procedimiento, ya que permite reducir la frecuencia de las crisis, ya sean tónica o átona, tónico-clónicas, ausencia o lóbulo frontal crisis parciales complejas. Objetivo: El objetivo de esta revisión de la literatura es discutir los detalles técnicos, modali- 94 Trabajo Original Revista Chilena de Neurocirugía 42: 2016 dades, riesgos, complicaciones, resultados y de pronóstico de callosotomía basado en la revisión crítica de la literatura y la experiencia de los autores. Casuística y Métodos: Se realizó la consulta bibliográfica, utilizando la base de datos MEDLINE, LILACS, SciELO, que utiliza el lenguaje como criterios de selección, la elección de los artículos recientes preferiblemente en portugués, español o Inglés, con el año de publicación superior a 2000. Conclusión: De acuerdo con la experiencia y las referencias del autor, callosotomía es un procedimiento seguro cuando indicado para casos seleccionados y la tasa de éxito es proporcional a la extensión de la resección del cuerpo calloso. A mayor resección puede reducir la frecuencia de las crisis, sin embargo, la morbilidad puede ser también mayor. No hay ningún estudio que compara la estimulación del nervio vago frente a frente callosotomía VNS más callososotomy, lo que sería la futura necesaria para una importante fuente de datos sobre este tema. Palabras clave: Epilepsia refractaria, epilepsia resistente a fármacos, Cuerpo calloso. Introduction loso marginal arteries. MRI) and fiber tractography, Hoffer and In over 60% of cases, callosotomy Frahm23 showed the trajectory of the fi- Corpus callosotomy is a palliative sur- shows satisfactory results for the pur- ber, and concluded that the corpus cal- gical approach that aims to control po- pose of treatment. In these patients, losum may be classified in five portions tentially harmful seizures, for instance, there is a decrease in the frequency of from anterior to posterior, which have atonic or drop seizures, preventing the seizures and improved quality of life4,32. different fiber compositions: spread of epileptic electrical activity4. The materials needed to perform a cal- Region 1: Anterior portion or genu; This technique was described by Van losotomy can be found in all hospitals Region 2: Anterior portion of the mid- Wagnen and Dandy16,56 and was high- and include a simple headlight and bin- dle third; lighted as a surgical method after 60s. ocular loupes or microscope, self-re- Region 3: Posterior portion of the mid- In the following decades, Bogen re- tention brain retractor, bipolar cauteri- dle third; introduced the callosotomy6 and later zation, and simple micro instruments58. Region 4: Isthmus of corpus callosum was reduced indication due to the use Region 5: Splenium. of vagal nerve stimulation (VNS). The disconnective syndrome, the con- Casuistry and Methods There are two types of fibers in the sequence of the section of the corpus corpus callosum: small fibers, mainly callosum fibers, it was proven by ex- It was performed bibliographical consul- connecting association cortical areas, perimental callosotomy in monkeys28,29. tation, using the databases MEDLINE, found in the rostrum, genu and anterior Although VNS results have shown mi- LILACS, SciELO, utilizing language as body and large diameter fibers in the nor complications, some patients con- selection criteria, choosing preferably posterior part of the splenium and in tinue to have atonic seizures, tonic and recent articles in portuguese, spanish the body, where interhemispheric sen- clonic seizures, even after treatment. or english, with publication year higher sory fibers cross the commissure and In these cases, it would be indicated than 2000. exchange information at high speed1,2. the additional callosotomy. In Len- nox Gastaut Syndrome, both kinds of Vascularization surgery has been used, however few Anatomy of callosum body Over the inner ependymal surface, the authors have used for disconnection drainage veins are spreaded, which of partial lateral syndromes seconda- The corpus callosum is the principal drains posteriorly to basal vein of rily generalized. If we consider only interhemispheric commissure. Embryo- Rosenthal and internal cerebral veins59. the refractory atonic seizures, there is logically, it arises in the brain of placen- The arterial vascularization comes from no superiority between these surgical tal mammals as an elongated midline pericallosal, callosomarginal and fronto methods, even VNS presenting minor structure composed of 2-3 x 108 fibers polar arteries by perforating arteries complications4,17. horizontal interconnecting homotopical The most important complications of and heterotopical cortical areas2,23,24. Callosum fibers corpus callosum transection are mu- The mature corpus callosum contains There are two enlargement of fibers tism, the disconnection syndrome and myelinated (70%) and unmyelinated fi- that forms the forceps: posteriorly this hemiparesis35. bers (30%), glial cells (astrocytes and enlargement of white fibers forms the This article aims to clarify technical de- oligodendrocytes), and neurons5,31,43-45 forceps major and at the anterior por- tails about callosotomy, allowing avoid and normally the callosum body has 7.5 tion there is a continuous enlargement damaging to important neural struc- - 9 cm in length and 2.5 - 3 in height and laterally to the forceps minor. tures as fornix, ventricle wall, arteries, the 2/3 that we need to perform calloso- The fibers of callosum body are as- thalamic connections, forceps minor tomy is almost five to six centimeters21. sociative white fibers with connections and major. A serious complication and with striatum in inferior middle anterior cause of postoperative death is injury Regions portion, limbic system, and between the to vessels close to the corpus callosum, By means studies with diffusion ten- motor fibers of the two hemispheres. as the veins and pericallosal and cal- sor magnetic resonance